This proposal seeks support for the further development of a new sensor technology that enables in-situ or in-vivo remote query real time measurement of physical and chemical parameters. In response to a magnetic field impulse the ribbon-shaped magnetoelastic sensors efficiently convert magnetic energy to elastic energy, which mechanically deforms the sensor. Since the material is magnetostrictive, the mechanical deformation acts to generate a time-varying magnetic flux that can be detected remotely with a pick-up coil. The mechanical deformation demonstrates a resonance the frequency of which is dependent upon sensor mass loading. Hence by combining a pH sensitive polymer with the magnetoelastic substrate a wireless, passive, inexpensive pH sensor is achieved. In Phase I we have demonstrated the feasibility of magnetoelastic sensors for remote query measurement of pH independently of background salt concentration, and reduced the sensor monitoring electronics to a notebook scale. The key goals of Phase II include a further extension in signal processing capability with miniaturization of the electronics package, optimization of polymer composition and response time, design and fabrication of a capsule within which the sensor is placed for introduction into the esophagus, and evaluation of sensor performance when used for in-vivo pH measurements (in pigs). PROPOSED COMMERCIAL APPLICATION: Wireless in-vivo measurement of gastric pH from passive, inexpensive disposable sensors would be a great improvement over current technology for monitoring of esophageal symptoms which require a trans-nasal catheter. The wireless, remote query nature of the sensor technology would also find great utility for in-situ monitoring of biological chemical analyte concentrations such as glucose.